Compact camera module

ABSTRACT

A compact camera module that contains a generally planar base on which is mounted a lens barrel is provided. The base, barrel, or both are molded from a polymer composition that includes a thermotropic liquid crystalline polymer and a plurality of mineral fibers (also known as “whisker”). The mineral fibers have a median width of from about 1 to about 35 micrometers and constitute from about 5 wt. % to about 60 wt. % of the polymer composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.14/052,800, filed on Oct. 14, 2013, which claims priority to U.S.Provisional Application Ser. No. 61/779,260, filed on Mar. 13, 2013,which are incorporated herein in their entirety by reference thereto.

BACKGROUND OF THE INVENTION

Compact camera modules (“CCM”) are often employed in mobile phones,laptop computers, digital cameras, digital video cameras, etc. thatcontain a plastic lens barrel disposed on a base. Because conventionalplastic lenses could not withstand solder reflow, camera modules werenot typically surface mounted. Recently, however, attempts have beenmade to use liquid crystalline polymers having a high heat resistancefor the molded parts of a compact camera module, such as the lens barrelor the base on which it is mounted. To improve the mechanical propertiesof such polymers, it is known to add a plate-like substance (e.g., talc)and milled glass. Although strength and elastic modulus can be improvedin this manner, problems are still encountered when attempting to usesuch materials in compact camera modules due to their small dimensionaltolerance. For example, the mechanical properties are often poor or notuniform, which leads to poor filing and a lack of dimensional stabilityin the molded part. Further, an increase in the amount of milled glassto improve mechanical properties can result in a surface that is toorough, which can lead to errors in the camera performance and sometimescause unwanted particle generation.

As such, a need exists for a polymer composition that can be readilyemployed in the molded parts of compact camera modules, and yet stillachieve good mechanical properties.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a compactcamera module is disclosed that comprises a generally planar base onwhich is mounted a lens barrel. The base, barrel, or both have athickness of about 500 micrometers or less and are molded from a polymercomposition that comprises a thermotropic liquid crystalline polymer anda plurality of mineral fibers. The mineral fibers have a median width offrom about 1 to about 35 micrometers and constitute from about 5 wt. %to about 60 wt. % of the polymer composition.

Other features and aspects of the present invention are set forth ingreater detail below.

BRIEF DESCRIPTION OF THE FIGURES

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIGS. 1-2 are perspective and front views of a compact camera module(“CCM”) that may be formed in accordance with one embodiment of thepresent invention; and

FIG. 3 is a schematic illustration of one embodiment of an extruderscrew that may be used to form the polymer composition of the presentinvention.

DETAILED DESCRIPTION

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention.

Generally speaking, the present invention is directed to a compactcamera module (“CCM”), such as those commonly employed in wirelesscommunication devices (e.g., cellular telephone). The camera modulecontains a generally planar base on which is mounted a lens barrel. Thebase and/or barrel are formed form a polymer composition that contains aliquid crystalline polymer and a plurality of mineral fibers (also knownas “whiskers”). Examples of such mineral fibers include those that arederived from silicates, such as neosilicates, sorosilicates,inosilicates (e.g., calcium inosilicates, such as wollastonite; calciummagnesium inosilicates, such as tremolite; calcium magnesium ironinosilicates, such as actinolite; magnesium iron inosilicates, such asanthophyllite; etc.), phyllosilicates (e.g., aluminum phyllosilicates,such as palygorskite), tectosilicates, etc.; sulfates, such as calciumsulfates (e.g., dehydrated or anhydrous gypsum); mineral wools (e.g.,rock or slag wool); and so forth. Particularly suitable areinosilicates, such as wollastonite fibers available from Nyco Mineralsunder the trade designation NYGLOS® (e.g., NYGLOS® 4W or NYGLOS® 8).

The mineral fibers may have a median width (e.g., diameter) of fromabout 1 to about 35 micrometers, in some embodiments from about 2 toabout 20 micrometers, in some embodiments from about 3 to about 15micrometers, and in some embodiments, from about 7 to about 12micrometers. The mineral fibers may also have a narrow sizedistribution. That is, at least about 60% by volume of the fibers, insome embodiments at least about 70% by volume of the fibers, and in someembodiments, at least about 80% by volume of the fibers may have a sizewithin the ranges noted above. Without intending to be limited bytheory, it is believed that mineral fibers having the sizecharacteristics noted above can more readily move through moldingequipment, which enhances the distribution within the polymer matrix andminimizes the creation of surface defects. In addition to possessing thesize characteristics noted above, the mineral fibers may also have arelatively high aspect ratio (average length divided by median width) tohelp further improve the mechanical properties and surface quality ofthe resulting polymer composition. For example, the mineral fibers mayhave an aspect ratio of from about 1 to about 50, in some embodimentsfrom about 2 to about 20, and in some embodiments, from about 4 to about15. The volume average length of such mineral fibers may, for example,range from about 1 to about 200 micrometers, in some embodiments fromabout 2 to about 150 micrometers, in some embodiments from about 5 toabout 100 micrometers, and in some embodiments, from about 10 to about50 micrometers.

Through the use of a liquid crystalline polymer and mineral fibers ofthe size noted above, the present inventors have discovered that theresulting polymer composition is able to achieve good strength and asmooth surface, which enables it to be uniquely suited for the smallmolded parts of a compact camera module. For example, the base may havea thickness of about 500 micrometers or less, in some embodiments fromabout 100 to about 450 micrometers, and in some embodiments, from about200 to about 400 micrometers. Likewise, the lens barrel may have a wallthickness of about 500 micrometers or less, in some embodiments fromabout 100 to about 450 micrometers, and in some embodiments, from about200 to about 400 micrometers. When formed from the polymer compositionof the present invention, the ratio of the thickness of the base and/orlens barrel to the volume average length of the mineral fibers may befrom about 1 to about 50, in some embodiments from about 2 to about 30,and in some embodiments, from about 5 to about 15.

The relative amount of the mineral fibers in the polymer composition isalso selectively controlled to help achieve the desired mechanicalproperties without adversely impacting other properties of thecomposition, such as its smoothness when formed into a molded part. Forexample, mineral fibers typically constitute from about 5 wt. % to about60 wt. %, in some embodiments from about 10 wt. % to about 50 wt. %, andin some embodiments, from about 20 wt. % to about 40 wt. % of thepolymer composition. In addition to fibers, the polymer composition ofthe present invention employs at least one thermotropic liquidcrystalline polymer, which has a high degree of crystallinity thatenables it to effectively fill the small spaces of the mold used to formthe base and/or lens barrel of a compact camera module. While theconcentration of the liquid crystalline polymers may generally varybased on the presence of other optional components, they are typicallypresent in an amount of from about 25 wt. % to about 95 wt. %, in someembodiments from about 30 wt. % to about 80 wt. %, and in someembodiments, from about 40 wt. % to about 70 wt. %.

Various embodiments of the present invention will now be described inmore detail.

I. Liquid Crystalline Polymer

The thermotropic liquid crystalline polymer generally has a high degreeof crystallinity that enables it to effectively fill the small spaces ofa mold. Suitable thermotropic liquid crystalline polymers may includearomatic polyesters, aromatic poly(esteram ides), aromaticpoly(estercarbonates), aromatic polyam ides, etc., and may likewisecontain repeating units formed from one or more aromatichydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols,aromatic aminocarboxylic acids, aromatic amines, aromatic diamines,etc., as well as combinations thereof.

Liquid crystalline polymers are generally classified as “thermotropic”to the extent that they can possess a rod-like structure and exhibit acrystalline behavior in its molten state (e.g., thermotropic nematicstate). Such polymers may be formed from one or more types of repeatingunits as is known in the art. The liquid crystalline polymer may, forexample, contain one or more aromatic ester repeating units, typicallyin an amount of from about 60 mol. % to about 99.9 mol. %, in someembodiments from about 70 mol. % to about 99.5 mol. %, and in someembodiments, from about 80 mol. % to about 99 mol. % of the polymer. Thearomatic ester repeating units may be generally represented by thefollowing Formula (I):

wherein,

ring B is a substituted or unsubstituted 6-membered aryl group (e.g.,1,4-phenylene or 1,3-phenylene), a substituted or unsubstituted6-membered aryl group fused to a substituted or unsubstituted 5- or6-membered aryl group (e.g., 2,6-naphthalene), or a substituted orunsubstituted 6-membered aryl group linked to a substituted orunsubstituted 5- or 6-membered aryl group (e.g., 4,4-biphenylene); and

Y₁ and Y₂ are independently O, C(O), NH, C(O)HN, or NHC(O).

Typically, at least one of Y₁ and Y₂ are C(O). Examples of such aromaticester repeating units may include, for instance, aromatic dicarboxylicrepeating units (Y₁ and Y₂ in Formula I are C(O)), aromatichydroxycarboxylic repeating units (Y₁ is O and Y₂ is C(O) in Formula I),as well as various combinations thereof.

Aromatic dicarboxylic repeating units, for instance, may be employedthat are derived from aromatic dicarboxylic acids, such as terephthalicacid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenylether-4,4′-dicarboxylic acid, 1,6-naphthalenedicarboxylic acid,2,7-naphthalenedicarboxylic acid, 4,4′-dicarboxybiphenyl,bis(4-carboxyphenyl)ether, bis(4-carboxyphenyl)butane,bis(4-carboxyphenyl)ethane, bis(3-carboxyphenyl)ether,bis(3-carboxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl andhalogen substituents thereof, and combinations thereof. Particularlysuitable aromatic dicarboxylic acids may include, for instance,terephthalic acid (“TA”), isophthalic acid (“IA”), and2,6-naphthalenedicarboxylic acid (“NDA”). When employed, repeating unitsderive from aromatic dicarboxylic acids (e.g., IA, TA, and/or NDA)typically constitute from about 5 mol. % to about 60 mol. %, in someembodiments from about 10 mol. % to about 55 mol. %, and in someembodiments, from about 15 mol. % to about 50% of the polymer.

Aromatic hydroxycarboxylic repeating units may also be employed that arederived from aromatic hydroxycarboxylic acids, such as, 4-hydroxybenzoicacid; 4-hydroxy-4′-biphenylcarboxylic acid; 2-hydroxy-6-naphthoic acid;2-hydroxy-5-naphthoic acid; 3-hydroxy-2-naphthoic acid;2-hydroxy-3-naphthoic acid; 4′-hydroxyphenyl-4-benzoic acid;3′-hydroxyphenyl-4-benzoic acid; 4′-hydroxyphenyl-3-benzoic acid, etc.,as well as alkyl, alkoxy, aryl and halogen substituents thereof, andcombination thereof. Particularly suitable aromatic hydroxycarboxylicacids are 4-hydroxybenzoic acid (“HBA”) and 6-hydroxy-2-naphthoic acid(“HNA”). When employed, repeating units derived from hydroxycarboxylicacids (e.g., HBA and/or HNA) typically constitute from about 10 mol. %to about 85 mol. %, in some embodiments from about 20 mol. % to about 80mol. %, and in some embodiments, from about 25 mol. % to about 75% ofthe polymer.

Other repeating units may also be employed in the polymer. In certainembodiments, for instance, repeating units may be employed that arederived from aromatic diols, such as hydroquinone, resorcinol,2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,1,6-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl (or 4,4′-biphenol),3,3′-dihydroxybiphenyl, 3,4′-dihydroxybiphenyl, 4,4′-dihydroxybiphenylether, bis(4-hydroxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryland halogen substituents thereof, and combinations thereof. Particularlysuitable aromatic diols may include, for instance, hydroquinone (“HQ”)and 4,4′-biphenol (“BP”). When employed, repeating units derived fromaromatic diols (e.g., HQ and/or BP) typically constitute from about 1mol. % to about 30 mol. %, in some embodiments from about 2 mol. % toabout 25 mol. %, and in some embodiments, from about 5 mol. % to about20% of the polymer. Repeating units may also be employed, such as thosederived from aromatic amides (e.g., acetaminophen (“APAP”)) and/oraromatic amines (e.g., 4-aminophenol (“AP”), 3-aminophenol,1,4-phenylenediamine, 1,3-phenylenediamine, etc.). When employed,repeating units derived from aromatic amides (e.g., APAP) and/oraromatic amines (e.g., AP) typically constitute from about 0.1 mol. % toabout 20 mol. %, in some embodiments from about 0.5 mol. % to about 15mol. %, and in some embodiments, from about 1 mol. % to about 10% of thepolymer. It should also be understood that various other monomericrepeating units may be incorporated into the polymer. For instance, incertain embodiments, the polymer may contain one or more repeating unitsderived from non-aromatic monomers, such as aliphatic or cycloaliphatichydroxycarboxylic acids, dicarboxylic acids, diols, amides, amines, etc.Of course, in other embodiments, the polymer may be “wholly aromatic” inthat it lacks repeating units derived from non-aromatic (e.g., aliphaticor cycloaliphatic) monomers.

Although not necessarily required, the liquid crystalline polymer may bea “low naphthenic” polymer to the extent that it contains a minimalcontent of repeating units derived from naphthenic hydroxycarboxylicacids and naphthenic dicarboxylic acids, such asnaphthalene-2,6-dicarboxylic acid (“NDA”), 6-hydroxy-2-naphthoic acid(“HNA”), or combinations thereof. That is, the total amount of repeatingunits derived from naphthenic hydroxycarboxylic and/or dicarboxylicacids (e.g., NDA, HNA, or a combination of HNA and NDA) is typically nomore than 30 mol. %, in some embodiments no more than about 15 mol. %,in some embodiments no more than about 10 mol. %, in some embodiments nomore than about 8 mol. %, and in some embodiments, from 0 mol. % toabout 5 mol. % of the polymer (e.g., 0 mol. %). Despite the absence of ahigh level of conventional naphthenic acids, it is believed that theresulting “low naphthenic” polymers are still capable of exhibiting goodthermal and mechanical properties.

In one particular embodiment, the liquid crystalline polymer may beformed from repeating units derived from 4-hydroxybenzoic acid (“HBA”)and terephthalic acid (“TA”) and/or isophthalic acid (“IA”), as well asvarious other optional constituents. The repeating units derived from4-hydroxybenzoic acid (“HBA”) may constitute from about 10 mol. % toabout 80 mol. %, in some embodiments from about 30 mol. % to about 75mol. %, and in some embodiments, from about 45 mol. % to about 70% ofthe polymer. The repeating units derived from terephthalic acid (“TA”)and/or isophthalic acid (“IA”) may likewise constitute from about 5 mol.% to about 40 mol. %, in some embodiments from about 10 mol. % to about35 mol. %, and in some embodiments, from about 15 mol. % to about 35% ofthe polymer. Repeating units may also be employed that are derived from4,4′-biphenol (“BP”) and/or hydroquinone (“HQ”) in an amount from about1 mol. % to about 30 mol. %, in some embodiments from about 2 mol. % toabout 25 mol. %, and in some embodiments, from about 5 mol. % to about20% of the polymer. Other possible repeating units may include thosederived from 6-hydroxy-2-naphthoic acid (“HNA”),2,6-naphthalenedicarboxylic acid (“NDA”), and/or acetaminophen (“APAP”).In certain embodiments, for example, repeating units derived from HNA,NDA, and/or APAP may each constitute from about 1 mol. % to about 35mol. %, in some embodiments from about 2 mol. % to about 30 mol. %, andin some embodiments, from about 3 mol. % to about 25 mol. % whenemployed.

Regardless of the particular constituents and nature of the polymer, theliquid crystalline polymer may be prepared by initially introducing thearomatic monomer(s) used to form ester repeating units (e.g., aromatichydroxycarboxylic acid, aromatic dicarboxylic acid, etc.) and/or otherrepeating units (e.g., aromatic diol, aromatic amide, aromatic amine,etc.) into a reactor vessel to initiate a polycondensation reaction. Theparticular conditions and steps employed in such reactions are wellknown, and may be described in more detail in U.S. Pat. No. 4,161,470 toCalundann; U.S. Pat. No. 5,616,680 to Linstid, III, et al.; U.S. Pat.No. 6,114,492 to Linstid, III, et al.; U.S. Pat. No. 6,514,611 toShepherd, et al.; and WO 2004/058851 to Waggoner. The vessel employedfor the reaction is not especially limited, although it is typicallydesired to employ one that is commonly used in reactions of highviscosity fluids. Examples of such a reaction vessel may include astirring tank-type apparatus that has an agitator with a variably-shapedstirring blade, such as an anchor type, multistage type, spiral-ribbontype, screw shaft type, etc., or a modified shape thereof. Furtherexamples of such a reaction vessel may include a mixing apparatuscommonly used in resin kneading, such as a kneader, a roll mill, aBanbury mixer, etc.

If desired, the reaction may proceed through the acetylation of themonomers as known the art. This may be accomplished by adding anacetylating agent (e.g., acetic anhydride) to the monomers. Acetylationis generally initiated at temperatures of about 90° C. During theinitial stage of the acetylation, reflux may be employed to maintainvapor phase temperature below the point at which acetic acid byproductand anhydride begin to distill. Temperatures during acetylationtypically range from between 90° C. to 150° C., and in some embodiments,from about 110° C. to about 150° C. If reflux is used, the vapor phasetemperature typically exceeds the boiling point of acetic acid, butremains low enough to retain residual acetic anhydride. For example,acetic anhydride vaporizes at temperatures of about 140° C. Thus,providing the reactor with a vapor phase reflux at a temperature of fromabout 110° C. to about 130° C. is particularly desirable. To ensuresubstantially complete reaction, an excess amount of acetic anhydridemay be employed. The amount of excess anhydride will vary depending uponthe particular acetylation conditions employed, including the presenceor absence of reflux. The use of an excess of from about 1 to about 10mole percent of acetic anhydride, based on the total moles of reactanthydroxyl groups present is not uncommon.

Acetylation may occur in in a separate reactor vessel, or it may occurin situ within the polymerization reactor vessel. When separate reactorvessels are employed, one or more of the monomers may be introduced tothe acetylation reactor and subsequently transferred to thepolymerization reactor. Likewise, one or more of the monomers may alsobe directly introduced to the reactor vessel without undergoingpre-acetylation.

In addition to the monomers and optional acetylating agents, othercomponents may also be included within the reaction mixture to helpfacilitate polymerization. For instance, a catalyst may be optionallyemployed, such as metal salt catalysts (e.g., magnesium acetate, tin(I)acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassiumacetate, etc.) and organic compound catalysts (e.g., N-methylimidazole).Such catalysts are typically used in amounts of from about 50 to about500 parts per million based on the total weight of the recurring unitprecursors. When separate reactors are employed, it is typically desiredto apply the catalyst to the acetylation reactor rather than thepolymerization reactor, although this is by no means a requirement.

The reaction mixture is generally heated to an elevated temperaturewithin the polymerization reactor vessel to initiate meltpolycondensation of the reactants. Polycondensation may occur, forinstance, within a temperature range of from about 250° C. to about 400°C., in some embodiments from about 280° C. to about 395° C., and in someembodiments, from about 300° C. to about 380° C. For instance, onesuitable technique for forming the liquid crystalline polymer mayinclude charging precursor monomers and acetic anhydride into thereactor, heating the mixture to a temperature of from about 90° C. toabout 150° C. to acetylize a hydroxyl group of the monomers (e.g.,forming acetoxy), and then increasing the temperature to from about 250°C. to about 400° C. to carry out melt polycondensation. As the finalpolymerization temperatures are approached, volatile byproducts of thereaction (e.g., acetic acid) may also be removed so that the desiredmolecular weight may be readily achieved. The reaction mixture isgenerally subjected to agitation during polymerization to ensure goodheat and mass transfer, and in turn, good material homogeneity. Therotational velocity of the agitator may vary during the course of thereaction, but typically ranges from about 10 to about 100 revolutionsper minute (“rpm”), and in some embodiments, from about 20 to about 80rpm. To build molecular weight in the melt, the polymerization reactionmay also be conducted under vacuum, the application of which facilitatesthe removal of volatiles formed during the final stages ofpolycondensation. The vacuum may be created by the application of asuctional pressure, such as within the range of from about 5 to about 30pounds per square inch (“psi”), and in some embodiments, from about 10to about 20 psi.

Following melt polymerization, the molten polymer may be discharged fromthe reactor, typically through an extrusion orifice fitted with a die ofdesired configuration, cooled, and collected. Commonly, the melt isdischarged through a perforated die to form strands that are taken up ina water bath, pelletized and dried. In some embodiments, the meltpolymerized polymer may also be subjected to a subsequent solid-statepolymerization method to further increase its molecular weight.Solid-state polymerization may be conducted in the presence of a gas(e.g., air, inert gas, etc.). Suitable inert gases may include, forinstance, include nitrogen, helium, argon, neon, krypton, xenon, etc.,as well as combinations thereof. The solid-state polymerization reactorvessel can be of virtually any design that will allow the polymer to bemaintained at the desired solid-state polymerization temperature for thedesired residence time. Examples of such vessels can be those that havea fixed bed, static bed, moving bed, fluidized bed, etc. The temperatureat which solid-state polymerization is performed may vary, but istypically within a range of from about 250° C. to about 350° C. Thepolymerization time will of course vary based on the temperature andtarget molecular weight. In most cases, however, the solid-statepolymerization time will be from about 2 to about 12 hours, and in someembodiments, from about 4 to about 10 hours.

II. Optional Components

A. Conductive Filler

If desired, a conductive filler may be employed in the polymercomposition to help reduce the tendency to create a static electriccharge during a molding operation. In fact, the present inventors havediscovered that the presence of a controlled size and amount of themineral fibers, as noted above, can enhance the ability of theconductive filler to be dispersed within the liquid crystalline polymermatrix, thereby allowing allow for the use of relatively lowconcentrations of the conductive filler to achieve the desiredantistatic properties. Because it is employed in relatively lowconcentrations, however, the impact on thermal and mechanical propertiescan be minimized. In this regard, conductive fillers, when employed,typically constitute from about 0.1 wt. % to about 25 wt. %, in someembodiments from about 0.3 wt. % to about 10 wt. %, in some embodimentsfrom about 0.4 wt. % to about 3 wt. %, and in some embodiments, fromabout 0.5 wt. % to about 1.5 wt. % of the polymer composition.

Any of a variety of conductive fillers may generally be employed in thepolymer composition to help improve its antistatic characteristics.Examples of suitable conductive fillers may include, for instance, metalparticles (e.g., aluminum flakes), metal fibers, carbon particles (e.g.,graphite, expanded graphite, grapheme, carbon black, graphitized carbonblack, etc.), carbon nanotubes, carbon fibers, and so forth. Carbonfibers and carbon particles (e.g., graphite) are particularly suitable.When employed, suitable carbon fibers may include pitch-based carbon(e.g., tar pitch), polyacrylonitrile-based carbon, metal-coated carbon,etc. Desirably, the carbon fibers have a high purity in that theypossess a relatively high carbon content, such as a carbon content ofabout 85 wt. % or more, in some embodiments about 90 wt. % or more, andin some embodiments, about 93 wt. % or more. For instance, the carboncontent can be at least about 94% wt., such as at least about 95% wt.,such as at least about 96% wt., such at least about 97% wt., such aseven at least about 98% wt. The carbon purity is generally less than 100wt. %, such as less than about 99 wt. %. The density of the carbonfibers is typically from about 0.5 to about 3.0 g/cm³, in someembodiments from about 1.0 to about 2.5 g/cm³, and in some embodiments,from about 1.5 to about 2.0 g/cm³.

In one embodiment, the carbon fibers are incorporated into the matrixwith minimal fiber breakage. The volume average length of the fibersafter molding can generally be from about 0.1 mm to about 1 mm even whenusing a fiber having an initial length of about 3 mm. The average lengthand distribution of the carbon fibers can also be selectively controlledin the final polymer composition to achieve a better connection andelectrical pathway within the liquid crystalline polymer matrix. Theaverage diameter of the fibers can be from about 0.5 to about 30micrometers, in some embodiments from about 1 to about 20 micrometers,and in some embodiments, from about 3 to about 15 micrometers.

To improve dispersion within the polymer matrix, the carbon fibers maybe at least partially coated with a sizing agent that increases thecompatibility of the carbon fibers with the liquid crystalline polymer.The sizing agent may be stable so that it does not thermally degrade attemperatures at which the liquid crystalline polymer is molded. In oneembodiment, the sizing agent may include a polymer, such as an aromaticpolymer. For instance, the aromatic polymer may have a thermaldecomposition temperature of greater than about 300° C., such as greaterthan about 350° C., such as greater than about 400° C. As used herein,the thermal decomposition temperature of a material is the temperatureat which the material losses 5% of its mass during thermogravimetericanalysis as determined in accordance with ASTM Test E 1131 (or ISO Test11358). The sizing agent can also have a relatively high glasstransition temperature. For instance, the glass transition temperatureof the sizing agent can be greater than about 300° C., such as greaterthan about 350° C., such as greater than about 400° C. Particularexamples of sizing agents include polyimide polymers, aromatic polyesterpolymers including wholly aromatic polyester polymers, and hightemperature epoxy polymers. In one embodiment, the sizing agent mayinclude a liquid crystalline polymer. The sizing agent can be present onthe fibers in an amount of at least about 0.1% wt., such as in an amountof at least 0.2% wt., such as in an amount of at least about 0.1% wt.The sizing agent is generally present in an amount less than about 5%wt., such as in an amount of less than about 3% wt.

Another suitable conductive filler is an ionic liquid. One benefit ofsuch a material is that, in addition to being electrically conductive,the ionic liquid can also exist in liquid form during melt processing,which allows it to be more uniformly blended within the liquidcrystalline polymer matrix. This improves electrical connectivity andthereby enhances the ability of the composition to rapidly dissipatestatic electric charges from its surface.

The ionic liquid is generally a salt that has a low enough meltingtemperature so that it can be in the form of a liquid when meltprocessed with the liquid crystalline polymer. For example, the meltingtemperature of the ionic liquid may be about 400° C. or less, in someembodiments about 350° C. or less, in some embodiments from about 1° C.to about 100° C., and in some embodiments, from about 5° C. to about 50°C. The salt contains a cationic species and counterion. The cationicspecies contains a compound having at least one heteroatom (e.g.,nitrogen or phosphorous) as a “cationic center.” Examples of suchheteroatomic compounds include, for instance, quaternary oniums havingthe following structures:

wherein, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently selectedfrom the group consisting of hydrogen; substituted or unsubstitutedC₁-C₁₀ alkyl groups (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, etc.); substituted orunsubstituted C₃-C₁₄ cycloalkyl groups (e.g., adamantyl, cyclopropyl,cyclobutyl, cyclopentyl, cyclooctyl, cyclohexenyl, etc.); substituted orunsubstituted C₁-C₁₀ alkenyl groups (e.g., ethylene, propylene,2-methypropylene, pentylene, etc.); substituted or unsubstituted C₂-C₁₀alkynyl groups (e.g., ethynyl, propynyl, etc.); substituted orunsubstituted C₁-C₁₀ alkoxy groups (e.g., methoxy, ethoxy, n-propoxy,isopropoxy, n-butoxy, t-butoxy, sec-butoxy, n-pentoxy, etc.);substituted or unsubstituted acyloxy groups (e.g., methacryloxy,methacryloxyethyl, etc.); substituted or unsubstituted aryl groups(e.g., phenyl); substituted or unsubstituted heteroaryl groups (e.g.,pyridyl, furanyl, thienyl, thiazolyl, isothiazolyl, triazolyl,imidazolyl, isoxazolyl, pyrrolyl, pyrazolyl, pyridazinyl, pyrimidinyl,quinolyl, etc.); and so forth. In one particular embodiment, forexample, the cationic species may be an ammonium compound having thestructure N⁺R¹R²R³R⁴, wherein R¹, R², and/or R³ are independently aC₁-C₆ alkyl (e.g., methyl, ethyl, butyl, etc.) and R⁴ is hydrogen or aC₁-C₄ alkyl group (e.g., methyl or ethyl). For example, the cationiccomponent may be tri-butylmethylammonium, wherein R¹, R², and R³ arebutyl and R⁴ is methyl.

Suitable counterions for the cationic species may include, for example,halogens (e.g., chloride, bromide, iodide, etc.); sulfates or sulfonates(e.g., methyl sulfate, ethyl sulfate, butyl sulfate, hexyl sulfate,octyl sulfate, hydrogen sulfate, methane sulfonate, dodecylbenzenesulfonate, dodecylsulfate, trifluoromethane sulfonate,heptadecafluorooctanesulfonate , sodium dodecylethoxysulfate, etc.);sulfosuccinates; amides (e.g., dicyanamide); im ides (e.g.,bis(pentafluoroethyl-sulfonyl)imide, bis(trifluoromethylsulfonyl)imide,bis(trifluoromethyl)imide, etc.); borates (e.g., tetrafluoroborate,tetracyanoborate, bis[oxalato]borate, bis[salicylato]borate, etc.);phosphates or phosphinates (e.g., hexafluorophosphate, diethylphosphate,bis(pentafluoroethyl)phosphinate,tris(pentafluoroethyl)-trifluorophosphate,tris(nonafluorobutyl)trifluorophosphate, etc.); antimonates (e.g.,hexafluoroantimonate); aluminates (e.g., tetrachloroaluminate); fattyacid carboxylates (e.g., oleate, isostearate, pentadecafluorooctanoate,etc.); cyanates; acetates; and so forth, as well as combinations of anyof the foregoing. To help improve compatibility with the liquidcrystalline polymer, it may be desired to select a counterion that isgenerally hydrophobic in nature, such as imides, fatty acidcarboxylates, etc. Particularly suitable hydrophobic counterions mayinclude, for instance, bis(pentafluoroethylsulfonyl)imide,bis(trifluoromethylsulfonyl)imide, and bis(trifluoromethyl)imide.

In certain embodiments, a synergistic affect may be achieved by usingthe ionic liquid and a carbon filler (e.g., graphite, carbon fibers,etc.) in combination. Without intending to be limited by theory, thepresent inventor believes that the ionic liquid is able to readily flowduring melt processing to help provide a better connection andelectrical pathway between the carbon filler and the liquid crystallinepolymer matrix, thereby further reducing surface resistivity.

B. Glass Fillers

Glass fillers, which are not generally conductive, may also be employedin the polymer composition to help improve strength. For example, glassfillers may constitute from about 2 wt. % to about 40 wt. %, in someembodiments from about 5 wt. % to about 35 wt. %, and in someembodiments, from about 6 wt. % to about 30 wt. % of the polymercomposition. Glass fibers are particularly suitable for use in thepresent invention, such as those formed from E-glass, A-glass, C-glass,D-glass, AR-glass, R-glass, S1-glass, S2-glass, etc., as well asmixtures thereof. The median width of the glass fibers may be relativelysmall, such as from about 1 to about 35 micrometers, in some embodimentsfrom about 2 to about 20 micrometers, and in some embodiments, fromabout 3 to about 10 micrometers. When employed, it is believed that thesmall diameter of such glass fibers can allow their length to be morereadily reduced during melt blending, which can further improve surfaceappearance and mechanical properties. In the molded part, for example,the volume average length of the glass fibers may be relatively small,such as from about 10 to about 500 micrometers, in some embodiments fromabout 100 to about 400 micrometers, in some embodiments from about 150to about 350 micrometers, and in some embodiments, from about 200 toabout 325 micrometers. The glass fibers may also have a relatively highaspect ratio (average length divided by nominal diameter), such as fromabout 1 to about 100, in some embodiments from about 10 to about 60, andin some embodiments, from about 30 to about 50.

C. Particulate Fillers

Particulate fillers, which are not generally conductive, may also beemployed in the polymer composition to help achieve the desiredproperties and/or color. When employed, such particulate fillerstypically constitute from about 5% by weight to about 40% by weight, insome embodiments from about 10% by weight to about 35% by weight, and insome embodiments, from about 10% by weight to about 30% by weight of thepolymer composition. Particulate clay minerals may be particularlysuitable for use in the present invention. Examples of such clayminerals include, for instance, talc (Mg₃Si₄O₁₀(OH)₂), halloysite(Al₂Si₂O₅(OH)₄), kaolinite (Al₂Si₂O₅(OH)₄), illite ((K,H₃O)(Al,Mg,Fe)₂(Si,Al)₄O₁₀[(OH)₂,(H₂O)]), montmorillonite(Na,Ca)_(0.33)(Al,Mg)₂Si₄O₁₀(OH)₂·nH₂O), vermiculite((MgFe,Al)₃(Al,Si)₄O₁₀(OH)₂·4H₂O), palygorskite((Mg,Al)₂Si₄O₁₀(OH)·4(H₂O)), pyrophyllite (Al₂Si₄O₁₀(OH)₂), etc., aswell as combinations thereof. In lieu of, or in addition to, clayminerals, still other particulate fillers may also be employed. Forexample, other suitable particulate silicate fillers may also beemployed, such as mica, diatomaceous earth, and so forth. Mica, forinstance, may be a particularly suitable mineral for use in the presentinvention. As used herein, the term “mica” is meant to genericallyinclude any of these species, such as muscovite (KAl₂(AlSi₃)O₁₀(OH)₂),biotite (K(Mg,Fe)₃(AlSi₃)O₁₀(OH)₂), phlogopite (KMg₃(AlSi₃)O₁₀(OH)₂),lepidolite (K(Li,Al)₂₋₃(AlSi₃)O₁₀(OH)₂), glauconite(K,Na)(Al,Mg,Fe)₂(Si,Al )₄O₁₀(OH)₂), etc., as well as combinationsthereof.

D. Functional Compounds

If desired, functional compounds may also be employed in the presentinvention to, among other things, help reduce the melt viscosity of thepolymer composition. In one embodiment, for example, the polymercomposition of the present invention may contain a functional aromaticcompound. Such compounds typically contain one or more carboxyl and/orhydroxyl functional groups that can react with the polymer chain toshorten its length, thus reducing the melt viscosity. In certain cases,the compound may also be able to combine smaller chains of the polymertogether after they have been cut to help maintain the mechanicalproperties of the composition even after its melt viscosity has beenreduced. The functional aromatic compound may have the general structureprovided below in Formula (II):

or a metal salt thereof, wherein,

ring B is a 6-membered aromatic ring wherein 1 to 3 ring carbon atomsare optionally replaced by nitrogen or oxygen, wherein each nitrogen isoptionally oxidized, and wherein ring B may be optionally fused orlinked to a 5- or 6-membered aryl, heteroaryl, cycloalkyl, orheterocyclyl;

R₄ is OH or COOH;

R₅ is acyl, acyloxy (e.g., acetyloxy), acylamino (e.g., acetylamino),alkoxy, alkenyl, alkyl, amino, aryl, aryloxy, carboxyl, carboxyl ester,cycloalkyl, cycloalkyloxy, hydroxyl, halo, haloalkyl, heteroaryl,heteroaryloxy, heterocyclyl, or heterocycloxy;

m is from 0 to 4, in some embodiments from 0 to 2, and in someembodiments, from 0 to 1; and

n is from 1 to 3, and in some embodiments, from 1 to 2. When thecompound is in the form of a metal salt, suitable metal counterions mayinclude transition metal counterions (e.g., copper, iron, etc.), alkalimetal counterions (e.g., potassium, sodium, etc.), alkaline earth metalcounterions (e.g., calcium, magnesium, etc.), and/or main group metalcounterions (e.g., aluminum).

In one embodiment, for example, B is phenyl in Formula (II) such thatthe resulting phenolic compounds have the following general formula(III):

or a metal salt thereof, wherein,

R₄ is OH or COOH;

R₆ is acyl, acyloxy, acylamino, alkoxy, alkenyl, alkyl, amino, carboxyl,carboxyl ester, hydroxyl, halo, or haloalkyl; and

q is from 0 to 4, in some embodiments from 0 to 2, and in someembodiments, from 0 to 1. Particular examples of such phenolic compoundsinclude, for instance, benzoic acid (q is 0); 4-hydroxybenzoic acid (R₄is COOH, R₆ is OH, and q is 1); phthalic acid (R₄ is COOH, R₆ is COOH,and q is 1); isophthalic acid (R₄ is COOH, R₆ is COOH, and q is 1);terephthalic acid (R₄ is COOH, R₆ is COOH, and q is 1);2-methylterephthalic acid (R₄ is COOH, R₆ is COOH, and CH₃ and q is 2);phenol (R₄ is OH and q is 0); sodium phenoxide (R₄ is OH and q is 0);hydroquinone (R₄ is OH, R₆ is OH, and q is 1); resorcinol (R₄ is OH, R₆is OH, and q is 1); 4-hydroxybenzoic acid (R₄ is OH, R₆ is C(O)OH, and qis 1), etc., as well as combinations thereof.

In another embodiment, B is phenyl and R₅ is phenyl in Formula (II)above such that the diphenolic compounds have the following generalformula (IV):

or a metal salt thereof, wherein,

R₄ is COOH or OH;

R₆ is acyl, acyloxy, acylamino, alkoxy, alkenyl, alkyl, amino, aryl,aryloxy, carboxyl, carboxyl ester, cycloalkyl, cycloalkyloxy, hydroxyl,halo, haloalkyl, heteroaryl, heteroaryloxy, heterocyclyl, orheterocycloxy; and

q is from 0 to 4, in some embodiments from 0 to 2, and in someembodiments, from 0 to 1. Particular examples of such diphenoliccompounds include, for instance, 4-hydroxy-4′-biphenylcarboxylic acid(R₄ is COOH, R₆ is OH, and q is 1); 4′-hydroxyphenyl-4-benzoic acid (R₄is COOH, R₆ is OH, and q is 1); 3′-hydroxyphenyl-4-benzoic acid (R₄ isCOOH, R₆ is OH, and q is 1); 4′-hydroxyphenyl-3-benzoic acid (R₄ isCOOH, R₆ is OH, and q is 1); 4,4′-bibenzoic acid (R₄ is COOH, R₆ isCOOH, and q is 1); (R₄ is OH, R₆ is OH, and q is 1); 3,3′-biphenol (R₄is OH, R₆ is OH, and q is 1); 3,4′-biphenol (R₄ is OH, R₆ is OH, and qis 1); 4-phenylphenol (R₄ is OH and q is O); bis(4-hydroxyphenyl)ethane(R₄ is OH, R₆ is C₂(OH)₂phenol, and q is 1); tris(4-hydroxyphenyl)ethane(R₄ is OH, R₆ is C(CH₃)biphenol, and q is 1);4-hydroxy-4′-biphenylcarboxylic acid (R₄ is OH, R₆ is COOH, and q is 1);4′-hydroxyphenyl-4-benzoic acid (R₄ is OH, R₆ is COOH, and q is 1);3′-hydroxyphenyl-4-benzoic acid (R₄ is OH, R₆ is COOH, and q is 1);4′-hydroxyphenyl-3-benzoic acid (R₄ is OH, R₆ is COOH, and q is 1);etc., as well as combinations thereof.

In yet another embodiment, B is naphthenyl in Formula (II) above suchthat the resulting naphthenic compounds have the following generalformula (V):

or a metal salt thereof, wherein,

R₄ is OH or COOH;

R₆ is acyl, acyloxy, acylamino, alkoxy, alkenyl, alkyl, amino, aryl,aryloxy, carboxyl, carboxyl ester, cycloalkyl, cycloalkyloxy, hydroxyl,halo, haloalkyl, heteroaryl, heteroaryloxy, heterocyclyl, orheterocycloxy; and

q is from 0 to 4, in some embodiments from 0 to 2, and in someembodiments, from 0 to 1. Particular examples of such naphtheniccompounds include, for instance, 1-naphthoic acid (R₄ is COOH and q is0); 2-naphthoic acid (R₄ is COOH and q is 0); 2-hydroxy-6-naphthoic acid(R₄ is COOH, R₆ is OH, and q is 1); 2-hydroxy-5-naphthoic acid (R₄ isCOOH, R₆ is OH, and q is 1); 3-hydroxy-2-naphthoic acid (R₄ is COOH, R₆is OH, and q is 1); 2-hydroxy-3-naphthoic acid (R₄ is COOH, R₆ is OH,and q is 1); 2,6-naphthalenedicarboxylic acid (R₄ is COOH, R₆ is COOH,and q is 1); 2,3-naphthalenedicarboxylic acid (R₄ is COOH, R₆ is COOH,and q is 1); 2-hydroxy-naphthelene (R₄ is OH and q is 0);2-hydroxy-6-naphthoic acid (R₄ is OH, R₆ is COOH, and q is 1);2-hydroxy-5-naphthoic acid (R₄ is OH, R₆ is COOH, and q is 1);3-hydroxy-2-naphthoic acid (R₄ is OH, R₆ is COOH, and q is 1);2-hydroxy-3-naphthoic acid (R₄ is OH, R₆ is COOH, and q is 1);2,6-dihydroxynaphthalene (R₄ is OH, R₆ is OH, and q is 1);2,7-dihydroxynaphtalene (R₄ is OH, R₆ is OH, and q is 1);1,6-dihydroxynaphthalene (R₄ is OH, R₆ is OH, and q is 1), etc., as wellas combinations thereof.

In certain embodiments of the present invention, for example, thepolymer composition may contain an aromatic diol, such as hydroquinone,resorcinol, 4,4′-biphenol, etc., as well as combinations thereof. Whenemployed, such aromatic diols may constitute from about 0.01 wt. % toabout 1 wt. %, and in some embodiments, from about 0.05 wt. % to about0.4 wt. % of the polymer composition. An aromatic carboxylic acid mayalso be employed in certain embodiments, either alone or in conjunctionwith the aromatic diol. Aromatic carboxylic acids may constitute fromabout 0.001 wt. % to about 0.5 wt. %, and in some embodiments, fromabout 0.005 wt. % to about 0.1 wt. % of the polymer composition. Inparticular embodiments, a combination of an aromatic diol (R₄ and R₆ areOH in the formulae above) (e.g., 4,4′-biphenol) and an aromaticdicarboxylic acid (R₄ and R₆ are COOH in the formulae above) (e.g.,2,6-naphthelene dicarboxylic acid) is employed in the present inventionto help achieve the desired viscosity reduction.

In addition to those noted above, non-aromatic functional compounds mayalso be employed in the present invention. Such compounds may serve avariety of purposes, such as reducing melt viscosity. One suchnon-aromatic functional compound is water. If desired, water can beadded in a form that under process conditions generates water. Forexample, the water can be added as a hydrate that under the processconditions (e.g., high temperature) effectively “loses” water. Suchhydrates include alumina trihydrate, copper sulfate pentahydrate, bariumchloride dihydrate, calcium sulfate dehydrate, etc., as well ascombinations thereof. When employed, the hydrates may constitute fromabout 0.02 wt. % to about 2 wt. %, and in some embodiments, from about0.05 wt. % to about 1 wt. % of the polymer composition. In oneparticular embodiment, a mixture of an aromatic diol, hydrate, andaromatic dicarboxylic acid are employed in the composition. In suchembodiments, the weight ratio of hydrates to aromatic diols is typicallyfrom about 0.5 to about 8, in some embodiments from about 0.8 to about5, and in some embodiments, from about 1 to about 5.

E. Other Additives

Still other additives that can be included in the composition mayinclude, for instance, antimicrobials, pigments, antioxidants,stabilizers, surfactants, waxes, solid solvents, flame retardants,anti-drip additives, and other materials added to enhance properties andprocessability. Lubricants may also be employed in the polymercomposition that are capable of withstanding the processing conditionsof the liquid crystalline polymer without substantial decomposition.Examples of such lubricants include fatty acids esters, the saltsthereof, esters, fatty acid amides, organic phosphate esters, andhydrocarbon waxes of the type commonly used as lubricants in theprocessing of engineering plastic materials, including mixtures thereof.Suitable fatty acids typically have a backbone carbon chain of fromabout 12 to about 60 carbon atoms, such as myristic acid, palm iticacid, stearic acid, arachic acid, montanic acid, octadecinic acid,parinric acid, and so forth. Suitable esters include fatty acid esters,fatty alcohol esters, wax esters, glycerol esters, glycol esters andcomplex esters. Fatty acid amides include fatty primary amides, fattysecondary amides, methylene and ethylene bisam ides and alkanolam idessuch as, for example, palmitic acid amide, stearic acid amide, oleicacid amide, N,N′-ethylenebisstearamide and so forth. Also suitable arethe metal salts of fatty acids such as calcium stearate, zinc stearate,magnesium stearate, and so forth; hydrocarbon waxes, including paraffinwaxes, polyolefin and oxidized polyolefin waxes, and microcrystallinewaxes. Particularly suitable lubricants are acids, salts, or amides ofstearic acid, such as pentaerythritol tetrastearate, calcium stearate,or N,N′-ethylenebisstearamide. When employed, the lubricant(s) typicallyconstitute from about 0.05 wt. % to about 1.5 wt. %, and in someembodiments, from about 0.1 wt. % to about 0.5 wt. % (by weight) of thepolymer composition.

III. Formation

The liquid crystalline polymer, mineral fibers, and other optionaladditives may be melt processed or blended together within a temperaturerange of from about 250° C. to about 450° C., in some embodiments, fromabout 280° C. to about 400° C., and in some embodiments, from about 300°C. to about 380° C. to form the polymer composition. For example, thecomponents (e.g., liquid crystalline polymer, mineral fibers, etc.) maybe supplied separately or in combination to an extruder that includes atleast one screw rotatably mounted and received within a barrel (e.g.,cylindrical barrel) and may define a feed section and a melting sectionlocated downstream from the feed section along the length of the screw.

The extruder may be a single screw or twin screw extruder. Referring toFIG. 3, for example, one embodiment of a single screw extruder 80 isshown that contains a housing or barrel 114 and a screw 120 rotatablydriven on one end by a suitable drive 124 (typically including a motorand gearbox). If desired, a twin-screw extruder may be employed thatcontains two separate screws. The configuration of the screw is notparticularly critical to the present invention and it may contain anynumber and/or orientation of threads and channels as is known in theart. As shown in FIG. 3, for example, the screw 120 contains a threadthat forms a generally helical channel radially extending around a coreof the screw 120. A hopper 40 is located adjacent to the drive 124 forsupplying the liquid crystalline polymer and/or other materials (e.g.,mineral fibers) through an opening in the barrel 114 to the feed section132. Opposite the drive 124 is the output end 144 of the extruder 80,where extruded plastic is output for further processing.

A feed section 132 and melt section 134 are defined along the length ofthe screw 120. The feed section 132 is the input portion of the barrel114 where the liquid crystalline polymer, mineral fibers, and/or thefunctional compound are added. The melt section 134 is the phase changesection in which the liquid crystalline polymer is changed from a solidto a liquid. While there is no precisely defined delineation of thesesections when the extruder is manufactured, it is well within theordinary skill of those in this art to reliably identify the feedsection 132 and the melt section 134 in which phase change from solid toliquid is occurring. Although not necessarily required, the extruder 80may also have a mixing section 136 that is located adjacent to theoutput end of the barrel 114 and downstream from the melting section134. If desired, one or more distributive and/or dispersive mixingelements may be employed within the mixing and/or melting sections ofthe extruder. Suitable distributive mixers for single screw extrudersmay include, for instance, Saxon, Dulmage, Cavity Transfer mixers, etc.Likewise, suitable dispersive mixers may include Blister ring,Leroy/Maddock, CRD mixers, etc. As is well known in the art, the mixingmay be further improved by using pins in the barrel that create afolding and reorientation of the polymer melt, such as those used inBuss Kneader extruders, Cavity Transfer mixers, and Vortex IntermeshingPin mixers.

The mineral fibers can be added to the hopper 40 or at a locationdownstream therefrom. In one particular embodiment, the mineral fibersmay be added a location downstream from the point at which the liquidcrystalline polymer is supplied. In this manner, the degree to which thelength of the microfibers is reduced can be minimized, which helpsmaintain the desired aspect ratio. If desired, the ratio of the length(“L”) to diameter (“D”) of the screw may be selected to achieve anoptimum balance between throughput and maintenance of the mineral fiberaspect ratio. The L/D value may, for instance, range from about 15 toabout 50, in some embodiments from about 20 to about 45, and in someembodiments from about 25 to about 40. The length of the screw may, forinstance, range from about 0.1 to about 5 meters, in some embodimentsfrom about 0.4 to about 4 meters, and in some embodiments, from about0.5 to about 2 meters. The diameter of the screw may likewise be fromabout 5 to about 150 millimeters, in some embodiments from about 10 toabout 120 millimeters, and in some embodiments, from about 20 to about80 millimeters. The L/D ratio of the screw after the point at which themineral fibers are supplied may also be controlled within a certainrange. For example, the screw has a blending length (“L_(B)”) that isdefined from the point at which the fibers are supplied to the extruderto the end of the screw, the blending length being less than the totallength of the screw. The L_(B)/D ratio of the screw after the point atwhich the mineral fibers are supplied may, for instance, range fromabout 4 to about 20, in some embodiments from about 5 to about 15, andin some embodiments, from about 6 to about 10.

In addition to the length and diameter, other aspects of the extrudermay also be controlled. For example, the speed of the screw may beselected to achieve the desired residence time, shear rate, meltprocessing temperature, etc. For example, the screw speed may range fromabout 50 to about 800 revolutions per minute (“rpm”), in someembodiments from about 70 to about 150 rpm, and in some embodiments,from about 80 to about 120 rpm. The apparent shear rate during meltblending may also range from about 100 seconds⁻¹ to about 10,000seconds⁻¹, in some embodiments from about 500 seconds⁻¹ to about 5000seconds⁻¹, and in some embodiments, from about 800 seconds⁻¹ to about1200 seconds⁻¹. The apparent shear rate is equal to 4Q/πR³, where Q isthe volumetric flow rate (“m³/s”) of the polymer melt and R is theradius (“m”) of the capillary (e.g., extruder die) through which themelted polymer flows.

Regardless of the particular manner in which it is formed, the presentinventors have discovered that the resulting polymer composition canpossess excellent thermal properties. For example, the melt viscosity ofthe polymer composition may be low enough so that it can readily flowinto the cavity of a mold having small dimensions. In one particularembodiment, the polymer composition may have a melt viscosity of fromabout 0.1 to about 150 Pa-s, in some embodiments from about 0.5 to about120 Pa-s, and in some embodiments, from about 1 to about 100 Pa-s,determined at a shear rate of 1000 seconds⁻¹. Melt viscosity may bedetermined in accordance with ISO Test No. 11443 at a temperature thatis 15° C. higher than the melting temperature of the composition (e.g.,350° C.). The composition may also have a relatively high meltingtemperature. For example, the melting temperature of the polymer may befrom about 250° C. to about 400° C., in some embodiments from about 280°C. to about 395° C., and in some embodiments, from about 300° C. toabout 380° C.

IV. Compact Camera Module

Once formed, the polymer composition may be molded into a shaped partfor use in a compact camera module. For example, the shaped part may bemolded using a one-component injection molding process in which driedand preheated plastic granules are injected into the mold. Regardless ofthe technique employed, it has been discovered that the molded part ofthe present invention may have a relatively smooth surface, which may berepresented by its surface glossiness). For example, the surfaceglossiness as determined using a gloss meter at an angle of from about80° to about 85° may be about 35% or more, in some embodiments about 38%or more, and in some embodiments, from about 40% to about 60%.Conventionally, it was believed that parts having such a smooth surfacewould not also possess sufficiently good mechanical properties. Contraryto conventional thought, however, the molded part of the presentinvention has been found to possess excellent mechanical properties. Forexample, the part may possess a high weld strength, which is useful whenforming the thin part of a compact camera module. For example, the partmay exhibit a weld strength of from about 10 kilopascals (“kPa”) toabout 100 kPa, in some embodiments from about 20 kPa to about 80 kPa,and in some embodiments, from about 40 kPa to about 70 kPa, which is thepeak stress as determined in accordance with ISO Test No. 527(technically equivalent to ASTM D638) at 23° C.

The part may also possess a Charpy notched impact strength greater thanabout 3 kJ/m², greater than about 4 kJ/m², in some embodiments fromabout 5 to about 40 kJ/m², and in some embodiments, from about 6 toabout 30 kJ/m², measured at 23° C. according to ISO Test No. 179-1)(technically equivalent to ASTM D256, Method B). The tensile andflexural mechanical properties are also good. For example, the part mayexhibit a tensile strength of from about 20 to about 500 MPa, in someembodiments from about 50 to about 400 MPa, and in some embodiments,from about 100 to about 350 MPa; a tensile break strain of about 0.5% ormore, in some embodiments from about 0.6% to about 10%, and in someembodiments, from about 0.8% to about 3.5%; and/or a tensile modulus offrom about 5,000 MPa to about 20,000 MPa, in some embodiments from about8,000 MPa to about 20,000 MPa, and in some embodiments, from about10,000 MPa to about 15,000 MPa. The tensile properties may be determinedin accordance with ISO Test No. 527 (technically equivalent to ASTMD638) at 23° C. The part may also exhibit a flexural strength of fromabout 20 to about 500 MPa, in some embodiments from about 50 to about400 MPa, and in some embodiments, from about 100 to about 350 MPa; aflexural break strain of about 0.5% or more, in some embodiments fromabout 0.6% to about 10%, and in some embodiments, from about 0.8% toabout 3.5%; and/or a flexural modulus of from about 5,000 MPa to about20,000 MPa, in some embodiments from about 8,000 MPa to about 20,000MPa, and in some embodiments, from about 10,000 MPa to about 15,000 MPa.The flexural properties may be determined in accordance with ISO TestNo. 178 (technically equivalent to ASTM D790) at 23° C. The molded partmay also exhibit a deflection temperature under load (DTUL) of about200° C. or more, and in some embodiments, from about 200° C. to about280° C., as measured according to ASTM D648-07 (technically equivalentto ISO Test No. 75-2) at a specified load of 1.8 MPa.

In addition, the molded part can also have excellent antistaticbehavior, particularly when a conductive filler is included within thepolymer composition. Such antistatic behavior can be characterized by arelatively low surface and/or volume resistivity as determined inaccordance with IEC 60093. For example, the molded part may exhibit asurface resistivity of about 1×10¹⁵ ohms or less, in some embodimentsabout 1×10¹⁴ ohms or less, in some embodiments from about 1×10¹⁰ ohms toabout 9×10¹³ ohms, and in some embodiments, from about 1×10¹¹ to about1×10¹³ ohms. Likewise, the molded part may also exhibit a volumeresistivity of about 1×10¹⁵ ohm-m or less, in some embodiments fromabout 1×10¹⁰ ohm-m to about 9×10¹⁴ ohm-m, and in some embodiments, fromabout 1×10¹¹ to about 5×10¹⁴ ohm-m. Of course, such antistatic behavioris by no means required. For example, in some embodiments, the moldedpart may exhibit a relatively high surface resistivity, such as about1×10¹⁵ ohms or more, in some embodiments about 1×10¹⁶ ohms or more, insome embodiments from about 1×10¹⁷ ohms to about 9×10³⁰ ohms, and insome embodiments, from about 1×10¹⁸ to about 1×10²⁶ ohms.

The polymer composition and molded part of the present invention may beemployed in a wide variety of compact camera module configurations. Oneparticularly suitable compact camera module is shown in FIGS. 1-2. Asshown, a compact camera module 500 contains a lens assembly 504 thatoverlies a base 506. The base 506, in turn, overlies an optional mainboard 508. Due to their relatively thin nature, the base 506 and/or mainboard 508 are particularly suited to be molded from the polymercomposition of the present invention as described above. The lensassembly 504 may have any of a variety of configurations as is known inthe art. In one embodiment, for example, the lens assembly 504 is in theform of a hollow barrel that houses lenses 604, which are incommunication with an image sensor 602 positioned on the main board 508and controlled by a circuit 601. The barrel may have any of a variety ofshapes, such as rectangular, cylindrical, etc. In certain embodiments,the barrel may be formed from the polymer composition of the presentinvention and have a wall thickness within the ranges noted above. Itshould be understood that other parts of the camera module may also beformed from the polymer composition of the present invention. Forexample, as shown, a polymer film 510 (e.g., polyester film) and/orthermal insulating cap 502 may cover the lens assembly 504. In someembodiments, the film 510 and/or cap 502 may also be formed from thepolymer composition.

The present invention may be better understood with reference to thefollowing examples.

TEST METHODS

Melt Viscosity: The melt viscosity (Pa-s) may be determined inaccordance with ISO Test No. 11443 at a shear rate of 1000 s⁻¹ andtemperature 15° C. above the melting temperature (e.g., 350° C.) using aDynisco LCR7001 capillary rheometer. The rheometer orifice (die) had adiameter of 1 mm, length of 20 mm, L/D ratio of 20.1, and an entranceangle of 180° . The diameter of the barrel was 9.55 mm +0.005 mm and thelength of the rod was 233.4 mm.

Melting Temperature: The melting temperature (“Tm”) was determined bydifferential scanning calorimetry (“DSC”) as is known in the art. Themelting temperature is the differential scanning calorimetry (DSC) peakmelt temperature as determined by ISO Test No. 11357. Under the DSCprocedure, samples were heated and cooled at 20° C. per minute as statedin ISO Standard 10350 using DSC measurements conducted on a TA Q2000Instrument.

Deflection Temperature Under Load (“DTUL”): The deflection under loadtemperature was determined in accordance with ISO Test No. 75-2(technically equivalent to ASTM D648-07). More particularly, a teststrip sample having a length of 80 mm, thickness of 10 mm, and width of4 mm was subjected to an edgewise three-point bending test in which thespecified load (maximum outer fibers stress) was 1.8 Megapascals. Thespecimen was lowered into a silicone oil bath where the temperature israised at 2° C. per minute until it deflects 0.25 mm (0.32 mm for ISOTest No. 75-2).

Tensile Modulus, Tensile Stress, and Tensile Elongation: Tensileproperties are tested according to ISO Test No. 527 (technicallyequivalent to ASTM D638). Modulus and strength measurements are made onthe same test strip sample having a length of 80 mm, thickness of 10 mm,and width of 4 mm. The testing temperature is 23° C., and the testingspeeds are 1 or 5 mm/min.

Flexural Modulus, Flexural Stress, and Flexural Strain: Flexuralproperties are tested according to ISO Test No. 178 (technicallyequivalent to ASTM D790). This test is performed on a 64 mm supportspan. Tests are run on the center portions of uncut ISO 3167multi-purpose bars. The testing temperature is 23° C. and the testingspeed is 2 mm/min.

Notched Charpy Impact Strength: Notched Charpy properties are testedaccording to ISO Test No. ISO 179-1) (technically equivalent to ASTMD256, Method B). This test is run using a Type A notch (0.25 mm baseradius) and Type 1 specimen size (length of 80 mm, width of 10 mm, andthickness of 4 mm). Specimens are cut from the center of a multi-purposebar using a single tooth milling machine. The testing temperature is 23°C.

Weldline Strength: The weldline strength may be determined by firstforming an injection molded line grid array (“LGA”) connector (size of49 mm×39 mm×1 mm) from a polymer composition sample as is well known inthe art. Once formed, the LGA connector may be placed on a sampleholder. The center of the connector may be subjected to a tensile forceby a rod moving at a speed of 5.08 millimeters per minute. The peakstress may be recorded as an estimate of the weldline strength.

Surface Glossiness: A gloss meter may be used to measure the glossinessof a surface. Glossiness readings may be taken at two differentlocations of the surface at an incident light angle of 85° relative tothe surface of the part, with three repeat measurements at eachlocation. The average of the readings may be taken for calculating theglossiness. Any suitable gloss meter may be used to measure glossiness,such as Micro-TRI-Gloss from BYK Gardner GmbH.

EXAMPLE 1

Samples 1-5 are formed from various percentages of a liquid crystallinepolymer, wollastonite (Nyglos® 4W or 8), anhydrous calcium sulfate,lubricant (Glycolube™ P), conductive filler, and black colormasterbatch, as indicated in Table 1 below. The black color masterbatchcontains 80 wt. % liquid crystalline polymer and 20 wt. % carbon black.In Samples 1-5, the conductive filler includes carbon fibers. In Sample6, the conductive filler also includes graphite. Finally, in Sample 7,the conductive filler is an ionic liquid —i.e.,tri-n-butylmethylammonium bis(trifluoromethanesulfonyl)-imide (FC-4400from 3M). The liquid crystalline polymer in each of the samples isformed from HBA, HNA, TA, BP, and APAP, such as described in U.S. Pat.No. 5,508,374 to Lee, et al. A comparative sample (Comp. Sample 1) isalso formed without wollastonite. Compounding is performed using an18-mm single screw extruder. Parts are injection molded the samples intoplaques (60 mm×60 mm).

TABLE 1 Comp. Sample 1 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5Sample 6 Sample 7 LCP (wt. %) 47.2 77.2 67.2 57.2 67.2 37.2 56.4 36.4Glass Powder 10.0 — — — — — — (wt. %) Talc (wt. %) 30.0 — — — — — — —Lubricant (wt. %)  0.3  0.3  0.3  0.3  0.3  0.3  0.3  0.3 Vectra ® A625— — — — — 30.0 — 20.0 FC-4400 — — — — — —  0.8  0.8 Black Color 12.512.5 12.5 12.5 12.5 12.5 12.5 12.5 Masterbatch Nyglos ® 4W — 10.0 20.030.0 — 20.0 10.0 30.0 Nyglos ® 8 — — — — 20.0 — — — Anhydrous — — — — —— 20.0 — Calcium Sulfate

Some of the molded parts are also tested for thermal and mechanicalproperties. The results are set forth below in Table 2.

TABLE 2 Sample 6 Sample 7 Melt Viscosity at 48.6 51.6 1000 s⁻¹ and 350°C. (Pa-s) Melt Viscosity at 78.5 78.6 400 s⁻¹ and 350° C. (Pa-s) Tm (°C.) 330.4 329.7 DTUL @ 1.8 Mpa (° C.) 212.4 215.7 Ten. Brk stress (MPa)117.63 81.8 Ten. Modulus (MPa) 9,249 8,842 Ten. Brk strain (%) 2.5 1.5Flex Brk stress (MPa) 114 105 Flex modulus (MPa) 8,518 9,344 Flex Brkstrain (%) 2.6 1.9 Charpy Notched (KJ/m²) 6.1 1.7

EXAMPLE 2

Samples 8-9 are formed from various percentages of a liquid crystallinepolymer, wollastonite (Nyglos® 4W), lubricant (Glycolube™ P), mica,hydrated alumina (“ATH”), 4,4′-biphenol (“BP”), and2,6-naphthanlenedicarboxylic acid (“NDA”), as indicated in Table 3below. The liquid crystalline polymer in each of the samples is formedfrom 4-hydroxybenzoic acid (“HBA”), 2,6-hydroxynaphthoic acid (“HNA”),terephthalic acid (“TA”), and hydroquinone (“HQ”), such as described inU.S. Pat. No. 5,969,083 to Long, et al. NDA is employed in the polymerin an amount of 20 mol. %. Comparative samples (Comp. Samples 2 and 3)are also formed without wollastonite. Compounding is performed using an18-mm single screw extruder. Parts are injection molded the samples intoplaques (60 mm×60 mm).

TABLE 3 Comp. Comp. Sample Sample Sample 2 Sample 3 8 9 LCP (wt. %)67.57 67.57 67.57 67.57 Glass Powder (wt.) 10.00 10.00 — — Nyglos ® 4W —— 10.00 10.00 Mica (wt. %) 22.00 22.00 22.00 22.00 Lubricant (wt. %)0.10 0.10 0.10 0.10 Hydrated alumina 0.20 0.20 0.20 0.20 4,4′-biphenol0.10 0.10 0.10 0.10 2,6-naphthalenedicarboxy 0.03 0.03 0.03 0.03 acid

Some of the molded parts are also tested for thermal and mechanicalproperties. The results are set forth below in Table 4.

TABLE 4 Comp. Comp. Sample Sample Sample Sample 2 3 6 7 Melt Viscosityat 10 26 15 30 1000 s⁻¹ and 350° C. (Pa-s) Melt Viscosity at 13 34 22 41400 s⁻¹ and 350° C. (Pa-s) Tm (° C.) 340 316 339 318 DTUL @ 1.8 Mpa (°C.) 277 274 276 276 Charpy Notched (KJ/m²) 3.7 6.7 3.4 7.7 Ten. Brkstress (MPa) 118.4 136.5 114.0 138.1 Ten. Modulus (MPa) 14,280 12,45515,013 12,832 Ten. Brk strain (%) 1.4 2.97 1.1 2.46 Flex Brk stress(MPa) 159.52 175.52 158.31 180.69 Flex modulus (MPa) 14,786 12,93515,546 13,489 Flex Brk strain (%) 2.3 3.19 2.0 3.0 Weldline Strength(lbf) 6.6 8.2 6.0 8.0

EXAMPLE 3

Sample 10 is formed from a liquid crystalline polymer, wollastonite(Nyglos® 4W), lubricant (Glycolube™ P), talc, hydrated alumina (“ATH”),4,4′-biphenol (“BP”), 2,6-naphthanlenedicarboxylic acid (“NDA”), and ablack color masterbatch, as indicated in Table 5 below. The liquidcrystalline polymer in each of the samples is formed from4-hydroxybenzoic acid (“HBA”), 2,6-hydroxynaphthoic acid (“HNA”),terephthalic acid, and 4,4′-biphenol (“BP”). HNA is employed in thepolymer in an amount of 20 mol. %. Compounding is performed using an18-mm single screw extruder. Parts are injection molded the samples intoplaques (60 mm×60 mm).

TABLE 5 Sample 8 LCP (wt. %) 58.58 Nyglos ® 4W 18.00 Talc (wt. %) 18.00Lubricant (wt. %) 0.10 Hydrated alumina 0.20 4,4′-biphenol 0.102,6-naphthalenedicarboxy acid 0.03 Black Color Masterbatch 5.00

Molded parts are also tested for thermal and mechanical properties. Theresults are set forth below in Table 6.

TABLE 6 Sample 8 Melt Viscosity at 20.0 1000 s⁻¹ and 350° C. (Pa-s) MeltViscosity at 34.3 400 s⁻¹ and 350° C. (Pa-s) Tm (° C.) 343.79 DTUL @ 1.8Mpa (° C.) 274 Charpy Notched (KJ/m²) 2 Ten. Brk stress (MPa) 11 Ten.Modulus (MPa) 97 Ten. Brk strain (%) 8,254 Flex Brk stress (MPa) 2.02Flex modulus (MPa) 127 Flex Brk strain (%) 9,005 Weldline Strength (lbf)2.35

EXAMPLE 4

Samples 11-12 are formed from various percentages of a liquidcrystalline polymer, wollastonite (Nyglos® 8), talc, and black pigment(HCN-LC DU 005) as indicated in Table 7 below. The liquid crystallinepolymer in each of the samples is formed from 4-hydroxybenzoic acid(“HBA”), terephthalic acid (“TA”), 4,4′-Biphenol (“BP”), 2,6-naphthalenedicarboxylic acid (“NDA”) and hydroquinone (“HQ”), such as described inU.S. Pat. No. 5,969,083 to Long, et al. NDA is employed in the polymerin an amount of 20 mol. %. Compounding is performed using an 18-mmsingle screw extruder, with the wollastonite fibers being added atBarrel No. 6. Parts are injection molded the samples into plaques (60mm×60 mm).

TABLE 7 Sample 11 Sample 12 LCP (wt. %) 55.00 55.00 Nyglos ® 8 40.0030.00 Talc (wt. %) — 10.00 Black Pigment (wt. %) 5.00 5.00

Some of the molded parts are also tested for thermal and mechanicalproperties. The results are set forth below in Table 8.

TABLE 8 Sample 11 Sample 12 Melt Viscosity at 46.6 37.2 1000 s⁻¹ and350° C. (Pa-s) Melt Viscosity at 74.4 58.5 400 s⁻¹ and 350° C. (Pa-s) Tm(° C.) 330.6 331.6 DTUL @ 1.8 Mpa (° C.) 271 — Charpy Notched (KJ/m²)2.9 3.1 Ten. Brk stress (MPa) 85 114 Ten. Modulus (MPa) 15,042 14,389Ten. Brk strain (%) 0.8 1.4 Flex Brk stress (MPa) 130 141 Flex modulus(MPa) 15,903 15,343 Flex Brk strain (%) 1.3 1.7

These and other modifications and variations of the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

What is claimed is:
 1. A compact camera module that comprises a moldedpart, wherein the molded part of the compact camera module has athickness of about 500 micrometers or less and is molded from a polymercomposition that comprises a thermotropic liquid crystalline polymerthat constitutes from about 40 wt. % to about 80 wt. % of the polymercomposition; and a plurality of fibers consisting of mineral fibers,wherein the mineral fibers have a median width of from about 1 to about35 micrometers, and constitute from about 5 wt. % to about 40 wt. % ofthe polymer composition, and wherein the mineral fibers have an aspectratio of from about 2 to about
 20. 2. The compact camera module of claim1, wherein the thickness is from about 100 to about 450 micrometers. 3.The compact camera module of claim 1, wherein the liquid crystallinepolymer contains aromatic ester repeating units.
 4. The compact cameramodule of claim 3, wherein the aromatic ester repeating units arearomatic dicarboxylic acid repeating units, aromatic hydroxycarboxylicacid repeating units, or a combination thereof.
 5. The compact cameramodule of claim 3, wherein the polymer further contains aromatic diolrepeating units.
 6. The compact camera module of claim 1, wherein theliquid crystalline polymer contains repeating units derived from4-hydroxybenzoic acid, terephthalic acid, hydroquinone, 4,4′-biphenol,acetaminophen, 6-hydroxy-2-naphthoic acid, 2,6-naphthelene dicarboxylicacid, or a combination thereof.
 7. The compact camera module of claim 1,wherein at least about 60% by volume of the mineral fibers have adiameter of from about 1 to about 35 micrometers.
 8. The compact cameramodule of claim 1, wherein the mineral fibers have a median width offrom about 3 to about 15 micrometers.
 9. The compact camera module ofclaim 1, wherein the mineral fibers include a sulfate.
 10. The compactcamera module of claim 1, further comprising a conductive filler, glassfiller, clay mineral, or a combination thereof.
 11. The compact cameramodule of claim 1, further comprising a functional compound.
 12. Thecompact camera module of claim 11, wherein the functional compoundincludes an aromatic compound that is an aromatic diol, aromaticcarboxylic acid, or a combination thereof.
 13. The compact camera moduleof claim 11, wherein the functional compound includes a non-aromaticcompound that is a hydrate.
 14. The compact camera module of claim 1,wherein the composition has a melt viscosity of from about 0.1 to about80 Pa-s, as determined in accordance with ISO Test No. 11443 at a shearrate of 1000 seconds⁻¹ and temperature that is 15° C. above the meltingtemperature of the composition.
 15. The compact camera module of claim1, wherein the molded part has a surface glossiness of about 35% or moreat an incident light angle of 85°.
 16. The compact cameral module ofclaim 1, wherein the mineral fibers comprise mineral fibers derived froma silicate.
 17. The compact camera module of claim 16, wherein thesilicate is an inosilicate.
 18. The compact camera module of claim 17,wherein the inosilicate includes wollastonite.